update on merc 120

[trm]

Installed the rebuilt carb. Lost the spark when I screwed up the points attaching the new condenser. Put in new points set the dwell. For the first time ever, the old 120 started on the first cylinder to fire. Purred like a kitten after setting idle needles. Warmed her up and went from idle to 4400 rpm without missing a beat. Then trolled at idle for seven hours with occasional rev to keep her plugs clean. Best she's run since I've known her. Thanks for the help of all here to get her in shape.<br /><br />Late in the day she stumbled when trying to get up to speed at about 2500 rpm. Switched fuel tanks and ran better, but not great. At the end of the day, she would feel just ok at 3400 rpm and would run up to 4000-4200 without changing throttle position. Hmmmm. Both the fuel tanks have last year's fuel (with stablizer) and added some Berrymen's B12 one of you recommended this spring. My guess is that the fuel is less than pristine Thinking of just topping off tanks and continue 'till the old "fuel" is virtually fresh.<br />Am I risking other problem(s) that may not be fuel related?<br /><br />Thnks again,<br /><br />swabbie

 

[akriverrat]

Re: update on merc 120

kinda sounds like water in fuel. drain the filter and see if it helps.

 

[trm]

Re: update on merc 120

I thought that is what the Berryman's B12 was for (removal of water)??????<br /><br />swabbie

 

[iwldntli2u]

Re: update on merc 120

I would try an drain the old fuel and start with high octane. Sounds like maybe the choke is going wakie. Wire your choke open and let us know your results

 

[horndog]

Re: update on merc 120

drain the old fuel put fresh gas in there along with change any fuel filters you may have including the fuel pump!

 

[trm]

Re: update on merc 120

Hey SkiRob,<br />Have you experienced a choke closing for no good reason?<br /><br />swabbie

 

[iwldntli2u]

Re: update on merc 120

Yes i have. My setup has a spring loaded choke with a hose connected to the manifold. For some strange reason the spring would not heat up and open the choke like it should have. Instead it would stay open till i throttled it and then flap close. to fix it i just wired the sucker open.

 

[trm]

Re: update on merc 120

I'll take a look, but I don't think my choke ever closes. And the feel(and sound) of it when the tack drops is starvation. After all, I did the carb rebuild myself. May be that something wierd causes it to close once in a while; if it does I'll grab some wire. Thanks for the tip.<br /><br />swabbie

 

[iwldntli2u]

Re: update on merc 120

OK now we are getting to the story. Did you replace that little ball bearing in the bottom of the float. Are you correct the your float measurements were correct. What about the T bar and spring. Seals on your jets? You might want to recheck the work that was done on the carb. Did you start with your adjusment screww out 3 truns?

 

[trm]

Re: update on merc 120

Hey Rob,<br /><br />Thanks for the input. Did all of the things you mention paying VERY close attention to float level. Idle screws make her happy at about 1 1/2 turns. About the choke, mine has that large round chamber with a tube to the valve cover. The chamber cover has notches with "rich-lean" arrows. Cold, the lever off the choke butterfly rod just touches the bi-metal spring coil per the instructions. This is with the butterlies open. There is a piston in there with two notches around it. It is connected to the choke butterfly rod. I have no clues what activates that piston, guessing vacuum, but from where? Anyway I have yet to see the choke butterflys close at anytime or temp.<br /><br />Went fishing for four days over the 4th and all was great. She fires immediately when cold (no choke), idles smoothly (as smooth as a 4 banger canwhen trolling, but still stops at 3500 for about a minute until the fouling plug cleans up and then to 4200 cruise without touching the throttle. Runs great at any speed then until we troll again for any length of time. I am willing to accept this as her "style" as it doesn't bother me at all. Hell, I have to blow my nose once in awhile too If we didn't troll at all, she'd never miss a beat. But since I can't catch those 3 pound Koho above a 700 rpm idle...... <br /><br />swabbie